feature #48098 [HttpKernel] Resolve DateTime value using the Clock (GromNaN)

This PR was merged into the 6.3 branch.

Discussion
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[HttpKernel]  Resolve DateTime value using the Clock

| Q             | A
| ------------- | ---
| Branch?       | 6.3
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | TODO

In order to mock the current time in functional test cases by injecting a `Symfony\Component\Clock\MockClock` as `clock` service. This is necessary when a `DateTimeInterface` argument is not nullable and we expect the current date time by default.

Example when 2 routes are configured on the same controller with an optional parameter.
```php
class TvGridController
{
    #[Route('/', name: 'prime_now')]
    #[Route('/{date}', name: 'prime_date']
    public function prime(\DateTimeInterface $date)
    {
        return new Response('Grid for date: '.$date->format('Y-m-d'));
    }
}
```

Commits
-------

4917528d9a Resolve DateTime value using the clock

Author: nicolas-grekas

Resources/config/web.php

@@ -55,6 +55,9 @@
             ->tag('controller.argument_value_resolver', ['priority' => 100])
 
         ->set('argument_resolver.datetime', DateTimeValueResolver::class)
+            ->args([
+                service('clock')->nullOnInvalid(),
+            ])
             ->tag('controller.argument_value_resolver', ['priority' => 100])
 
         ->set('argument_resolver.request_attribute', RequestAttributeValueResolver::class)